Vajradhara (Tib: Dorje Chang) is the primordial buddha. When Buddha Shakyamuni attained enlightenment, the wisdom aspect of his realization was the truth body of the buddha, or Dharmakaya.
Vajradhara is blue in color like the primordial buddha Samantabhadra. The bell in his left hand symbolizes wisdom and the vajra in his right symbolizes the method of compassion. His arms are crossed signifying the union of wisdom and compassion.
Vajradhara is depicted in the center of the Drikung Kagyu refuge tree and is considered a significant figure throughout the Kagyu lineage. The dharmakaya depicted in the form of Vajradhara is the source of all the manifestations of enlightenment. Tilopa received the vajrayana teachings directly from Vajradhara. Therefore, the Kagyu lineage originated from the very nature of Buddhahood.